Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands |
Mar. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Accrued Expenses and Other Current Liabilities | ||
| Accrued employee compensation and benefits | $ 2,954 | $ 8,124 |
| Accrued external research and development expenses | 2,264 | 3,156 |
| Accrued manufacturing facility expenses | 382 | 339 |
| Accrued general and administrative expenses | 1,439 | 1,244 |
| Other | 548 | 554 |
| Accrued expenses and other current liabilities | $ 7,587 | $ 13,417 |